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form_fieldtype(3X) form_fieldtype(3X)
form_fieldtype - define validation-field types
#include <form.h> FIELDTYPE *new_fieldtype( bool (* const field_check)(FIELD *, const void *), bool (* const char_check)(int, const void *)); int free_fieldtype(FIELDTYPE *fieldtype); int set_fieldtype_arg( FIELDTYPE *fieldtype, void *(* const make_arg)(va_list *), void *(* const copy_arg)(const void *), void (* const free_arg)(void *)); int set_fieldtype_choice( FIELDTYPE *fieldtype, bool (* const next_choice)(FIELD *, const void *), bool (* const prev_choice)(FIELD *, const void *)); FIELDTYPE *link_fieldtype(FIELDTYPE *type1, FIELDTYPE *type2);
new_fieldtype The function new_fieldtype creates a new field type usable for data validation. Its parameters are function pointers: field_check This function checks the validity of an entered data string whenever the user attempts to leave a field. It has two arguments: • The (FIELD *) argument is passed in so the validation predicate can see the field's buffer, sizes and other attributes. • The second argument is an argument-block structure, about which more below. char_check This function validates input characters as they are entered. The form library passes it the character to be checked and a pointer to an argument-block structure. free_fieldtype The free_fieldtype function frees the space allocated for a given validation type by new_fieldtype. set_fieldtype_arg The function set_fieldtype_arg associates three storage- management functions with a field type: make_arg This function is automatically applied to the list of arguments you give set_field_type when attaching validation to a field. It stores the arguments in an allocated argument-block object which is used when validating input. copy_arg This function may be used by applications to copy argument- blocks. free_arg Frees an argument-block structure. You must supply the make_arg function. The other two are optional: you may supply NULL for them. In this case, the form library assumes that make_arg does not allocate memory but simply loads the argument into a single scalar value. set_fieldtype_choice The form driver requests REQ_NEXT_CHOICE and REQ_PREV_CHOICE assume that the possible values of a field form an ordered set, and provide the forms user with a way to move through the set. The set_fieldtype_choice function allows forms programmers to define successor and predecessor functions for the field type. These functions take the field pointer and an argument-block structure as arguments. link_fieldtype The function link_fieldtype creates a new field type from the two given types. They are connected by an logical 'OR'.
The pointer-valued routines return NULL on error. They set errno according to their success: E_OK The routine succeeded. E_BAD_ARGUMENT Routine detected an incorrect or out-of-range argument. E_SYSTEM_ERROR System error occurred, e.g., malloc failure. The integer-valued routines return one of the following codes on error: E_OK The routine succeeded. E_BAD_ARGUMENT Routine detected an incorrect or out-of-range argument. E_CONNECTED The field is already connected to a form. E_CURRENT The field is the current field. E_SYSTEM_ERROR System error occurred (see errno(3)).
curses(3X), form(3X), form_field_validation(3X).
The header file <form.h> automatically includes the header file <curses.h>.
These routines emulate the System V forms library. They were not supported on Version 7 or BSD versions.
Juergen Pfeifer. Manual pages and adaptation for new curses by Eric S. Raymond.
This page is part of the ncurses (new curses) project.
Information about the project can be found at
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form_fieldtype(3X)